/*!	 weightedvalue.h
**	 A weighted value template
**
**	......... ... 2014 Ivan Mahonin
**
**	This package is free software; you can redistribute it and/or
**	modify it under the terms of the GNU General Public License as
**	published by the Free Software Foundation; either version 2 of
**	the License, or (at your option) any later version.
**
**	This package is distributed in the hope that it will be useful,
**	but WITHOUT ANY WARRANTY; without even the implied warranty of
**	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
**	General Public License for more details.
**
*/

#ifndef __SYNFIG_WEIGHTEDVALUE_H
#define __SYNFIG_WEIGHTEDVALUE_H

#include "real.h"
#include "type.h"
#include "value.h"

namespace synfig
{

template<typename T>
class WeightedValue
{
public:
    typedef T ValueType;
    Real weight;
    ValueType value;
    WeightedValue(): weight(), value() { }
    explicit WeightedValue(Real weight): weight(weight), value() { }
    explicit WeightedValue(Real weight, const ValueType &value): weight(weight), value(value) { }
};

namespace types_namespace
{
class TypeWeightedValueBase: public Type
{
public:
    virtual Type& get_contained_type() = 0;
    virtual ValueBase create_weighted_value(Real weight, const ValueBase &value) = 0;
    virtual Real extract_weight(const ValueBase &value) = 0;
    virtual ValueBase extract_value(const ValueBase &value) = 0;
};

template<typename T>
class TypeWeightedValue: public TypeWeightedValueBase
{
    static String to_string(const WeightedValue<T> &x)
    {
        return etl::strprintf("Weight (%f) %s", x.weight, value_to_string(x.value).c_str());
    }
    void initialize_vfunc(Description &description)
    {
        Type &type = get_type_alias(T()).type;
        type.initialize();

        Type::initialize_vfunc(description);
        description.name = "weighted_" + type.description.name;
        description.local_name = local_n("weighted") + String(" ") + type.description.local_name;
        register_all_but_compare<WeightedValue<T>, TypeWeightedValue<T>::to_string>();
    }
    Type& get_contained_type()
    {
        return get_type_alias(T()).type;
    }
    ValueBase create_weighted_value(Real weight, const ValueBase &value)
    {
        return WeightedValue<T>(weight, value.get(T()));
    };
    Real extract_weight(const ValueBase &value)
    {
        return value.get(WeightedValue<T>()).weight;
    };
    ValueBase extract_value(const ValueBase &value)
    {
        return value.get(WeightedValue<T>()).value;
    };
public:
    static TypeWeightedValue instance;
};

template<typename T>
TypeWeightedValue<T> TypeWeightedValue<T>::instance;

template<typename T>
TypeAlias< WeightedValue<T> > get_type_alias(WeightedValue<T> const&)
{
    return TypeAlias< WeightedValue<T> >(TypeWeightedValue<T>::instance);
}
}

}; // END of namespace synfig

#endif